This disclosure relates to the field of drinking vessels and the like, particularly drinking vessels or “tumblers” that are made of a hard plastic material and that have a dual wall construction for thermal insulation.
Conventional dual wall plastic drinking vessels or tumblers comprise an inner receptacle defined by a first circumferential wall, and an outer receptacle defined by a second circumferential wall. The first and second walls are separated by an air-filled space, and they are joined to each other at a peripheral rim or lip defining the open top of the tumbler. The juncture of the inner and outer walls at the peripheral rim is typically accomplished by a sonic welding process, or alternatively, by a suitable adhesive. It is important that the juncture provide a fluid-tight seal to prevent liquid from leaking into the space between the two walls. Obtaining a seal with good integrity by sonic welding or by an adhesive is sometimes problematical in a mass-produced item. Even with good initial quality, with repeated use and washing over time, the integrity of the seal may be degraded, leading to leakage of liquid into the space between the walls. With the inner and outer receptacles being more or less permanently joined, separating the two receptacles to clean the space is not a practical option. Consequently, the leakage of liquid into the inter-wall space typically requires the disposal of the vessel.
The need has therefore been felt for a dual wall vessel or tumbler that overcomes the above-noted shortcomings of the prior art. More specifically, there has been an as yet unmet need for a dual wall tumbler or the like that provides effective sealing between the walls, and that also allows at least a partial disassembly if the need arises to remove liquid that leaks into the inter-wall space.